1. Field of the Invention
The present invention relates to an information recording device and method which records user data in a recording medium having two or more recording layers each of which has a data area capable of recording information, such as a dual-layer DVD-R. Moreover, the present invention relates to a computer program product embodied therein for causing the computer to execute the information recording method which records user data in the recording medium having two or more recording layers each of which has a data area capable of recording information.
2. Description of the Related Art
As the recordable DVDs, there are the DVD-R which is a write-once optical disk, and the DVD+RW which is a rewritable optical disk. These DVD disks have high reproduction compatibility with the read-only DVD disk which is provided with the single layer on the single side for the reproduction only. The research and development of the recordable DVDs have been performed briskly for the high-speed access and the large storage capacity of the media.
Among them, there is the single-side dual-layer DVD+R disk (called the dual-layer DVD+R) which has high reproduction compatibility with the read-only DVD disk of the single-side dual-layer type which is provided for reproduction only. The storage capacity of the dual-layer DVD+R is 8.4 Gbytes, which is about twice the storage capacity of the conventional single-layer DVD+R which is 4.7 Gbytes. The recorded data in the dual-layer DVD-R can be read out by the DVD-ROM drive or the DVD player which is capable of reading the read-only DVD disk of the single-side dual-layer type. For example, the information recording device which records information in the recordable DVD is known from Japanese Laid-Open Patent Application No. 2001-126255.
There are the two addressing methods for the single-side dual-layer DVD disks: the Parallel Track Path method (called the PTP method) and the Opposite Track Path method (called the OTP method). In the PTP method, both the addresses of the track on the first layer and the addresses of the track on the second layer increase from the inner periphery to the outer periphery in a parallel manner. In the OTP method, the addresses of the track on the first layer increase from the inner periphery to the outer periphery while the addresses of the track on the second layer increase from the outer periphery to the inner periphery.
According to the PTP method, the starting position in the radial direction of the disk where the data area starts is the same for both the first layer and the second layer, and the physical sector number of the starting position is 30000h for both the first and second layers. Moreover, after the end of the data area, the lead-out area is arranged in the disk.
According to the OTP method, the starting position in the radial direction of the disk where the data area of the second layer starts is the same as the end position in the radial direction of the disk where the data area of the first layer ends. The physical sector number of the starting position of the data area of the second layer is equal to the bit-inverted address of the physical sector number of the end position of the data area of the first layer. When the data area of the first layer and the data area of the second layer are different in size, the difference region is included in the lead-out area of the disk.
For example, when the end address D1 of the data area of the first layer and the end address D2 of the data area of the second layer in the PTP disk are set to meet the condition D1>D2, the difference region D1-D2 is included in the lead-out area of the disk. Thus, when the user data are recorded in some region of one of the two recording layers, the user data are also recorded in the corresponding region of the other recording layer.
The purpose of such data recording is to avoid the problem that the data of the first layer cannot be read by the optical head when reproducing the data of the first layer. When the focused laser beam is directed to the second layer by chance during the seeking of the target address, the address information cannot be acquired from the second layer if the user data are not written to the second layer at the same radial position as the first layer of the disk. Consequently, the difficulty of the reproduction of the data of the first layer may arise. To avoid this problem, performing the above data recording is necessary.
Moreover, the logical address in the dual-layer DVD is continuously assigned from the starting address of the data area of the first layer. The logical address of the starting position of the data area of the second layer continuously follows the logical address of the end position of the data area of the first layer.
That is, when performing reproduction of the dual-layer DVD, the user specifies the target reproduction region of the dual-layer DVD using the logical address, so that the reproduction is allowed without being conscious of whether the reproduction region is located on the first layer or the second layer.
On the other hand, when performing recording of user data in the dual-layer DVD+R, the user specifies the target recording region of the dual-layer DVD+R using the logical address similar to the reproduction processing.
For this reason, when the user performs the data recording continuously, the recording is started from the starting address of the data area of the first layer. When the recording up to the end address of the data area of the first layer is completed, the recording will be continuously started from the starting address of the data area of the second layer.
Thus, the user can carry out the data recording of the dual-layer DVD+R without being conscious of whether the recording region is located on the first layer or the second layer.
However, there may be a case in which recording of user data is completed in the middle of the data area of the second layer. Or there may be a case in which recording of user data is completed in the middle of the data area of the first layer without recording any of the user data in the second layer at all.
If recording of user data is completed in the middle of the data area of the second layer, the non-recorded region is left in the data area of the second layer, which will cause the dual-layer DVD+R disk to lose reproduction compatibility with the read-only type DVD because of the non-recorded region left in the data area of the second layer.
Moreover, if the focused laser beam is directed to the second layer by chance during the seeking of the target address when reproducing the user data from the first layer, the address information cannot be acquired from the second layer. This is because the non-recorded region is left in the data area of the second layer, and the data are not written to the second layer at the same radial position as the first layer. In such a case, the problem that the user data of the first layer cannot be read arise. The same problem may arise when the recording of the user data is completed in the middle of the data area of the first layer without recording any of the user data in the second layer.